In construction projects it is desirable to have accurate square cuts on structural lumber. The hand-held circular saw is probably the most used tool for cutting in the field. Many devices, such as the carpenter's square, have been utilized in the past to improve the accuracy of square cuts made with hand-held circular saws. However, this approach requires the user to align two tools and consumes twice as much time per cut as it would to align a single tool. An improved hand-held circular saw which one can use by itself to make accurate square cuts is much needed.